This request is for funds to purchase a multimode live cell inverted fluorescence microscope. This instrument will serve as the primary light microscopic image collection system within the Department of Environmental and Occupational Health (EOH) of the Graduate School Public Health (GSPH). This new need for EOH is the result of: a) immediate and future recruitment of molecular toxicologists with live cell imaging needs; b) the expansion of existing programs within EOH to examine issues of environmental stress on the physiology of live cells and fluorescence in situ hybridization studies for chromosomal aberrations after environmental mutagens. These investigators are currently located in the Center for Environmental and Occupational Health and Toxicology (CEOHT) in Blawnox, PA that is 9 miles from the University of Pittsburgh GSPH and School of Medicine. There are no microscopic facilities that support live cell imaging nor is there an ability to collect images from low light samples such as in situ fluorescent hybridization. There is, however, a highly contemporary Center for Biological Imaging (CBI) directed by Simon Watkins, Ph.D. in the School of Medicine. Although plans are underway to move CEOHT onto the University of Pittsburgh campus in Oakland, PA, the likely new site will remain at a considerable distance from CBI. It is the intent of this request to establish a broad based platform of fluorescence imaging within CEOHT to: a) facilitate studies that otherwise could not tolerate travel between CEOHT and CBI; b) allow developmental work in imaging prior to execution of more sophisticated applications in heavily subscribed CBI; and c) enhance training of pre- and post- doctoral students by introducing routine fluorescence imaging in environmental health science. Accordingly a request is made to purchase a high quality, expandable optical platform able to sample several different fluorochromes with exquisite signal separation between chromes, a sensitive camera system able to perform quantitative analysis of extremely low light signals, the ability to collect images from live cells with minimal cell killing, and a computer system containing modules specifically designed for applications in environmental health science.